Asphalt (or bitumen) compositions are in widespread use as asphalt-aggregate blends for road paving, in roofing shingles, in hot applied asphalt roofing systems, and similar applications. A problem with such compositions is their tendency to become brittle at low temperatures and to become soft at high temperatures. Various additives, polymers, etc., have been utilized for the purpose of improving the high and low temperature characteristics of asphalt compositions, as well as to improve their toughness and durability. Tall oil, produced primarily as a byproduct of certain paper manufacturing processes, is widely used for this purpose, both as a direct additive and in its various modified forms, including saponified tall oil. However, most prior art processes for tall oil saponification have utilized added water (usually as a component of a caustic solution used in the saponification process) with the result that the saponified tall oil product often has a high water content. Water is deleterious to high temperature asphalt blending processes, since the water flashes off, resulting in the swelling of the asphalt, production of large quantities of steam vapor containing entrained light end components, leaching of hydrocarbons from the asphalt, etc. The prior art therefore discloses various attempts to produce asphalt blends, or other tall oil containing compositions utilizing a minimum of added water. Another limitation of the prior art has been a limit on the amount of saponified tall oil capable of being kept in solution with asphalt. Prior art methods did not address tall oil-asphalt compatibility.
U.S. Pat. No. 5,221,703 entitled "Engineered Modified Asphalt Cement" relates to a modified bituminous material containing asphalt, tall oil, a polymer (such as styrene butidiene, natural latex, etc.) and a strong base (preferably sodium hydroxide or potassium hydroxide). A small amount of water is present in the composition, either as water in a solution of the strong base, or water in a latex added as the polymer in the composition.
U.S. Pat. No. 1,813,454 entitled "Saponification" discloses a process for saponifying organic esters, particularly the esters of fatty acids, such as vegetable and animal fats. The process comprises treating the organic ester with substantially anhydrous alkali in the presence of an inert organic diluent in which the alcoholic component of the ester is substantially insoluble, and simultaneously removing the alcoholic component in a concentrated form by partial pressure distillation of the diluent and the alcoholic component.
U.S. Pat. No. 2,268,122 entitled "Road Tars or the Like and the Methods of Making Them" also discloses a process for substantially anhydrous saponification of fatty oils using an organic diluent such as kerosene.
U.S. Pat. No. 2,753,363 entitled "Method of Making Soap" relates to the manufacture of soap, and more particularly to an improved method of making a soap of relatively low moisture content wherein the saponification is carried out in two stages. In the first stage, a fatty acid mixture, or a mixture of fatty acids and glycerides, is reacted with a quantity of dry alkali metal carbonate that is sufficient to saponify a substantial proportion of the free fatty acids present in the raw material but insufficient to saponify all of the fatty materials present. Thereafter, in a second stage, saponification of the fatty material is completed with a concentrated aqueous caustic alkali.
U.S. Pat. No. 4,129,520 entitled "Soap Making" discloses a process for saponifying organic acid esters in fats from animal or vegetable sources in which process the organic acid esters are saponified with alkali metal hydroxide in a liquid reaction medium comprising a substantially water-free alkyl nitrile. The preferred anhydrous reaction media are acetonitrile and proprionitrile. The stated advantage of the anhydrous preparation method is that the solvent removal is less energy intensive than in aqueous processes. The preferred products of the process are soaps and detergents.
U.S. Pat. No. 4,874,432 entitled "Multigrade Asphalt Cement Product and Process" relates to a process for producing a multi-grade asphalt cement product. The process involves saponifying in liquefied asphalt, substantially free of water, at least one fatty acid and at least one resin acid with an alkali metal base, or by adding the already saponified acid to the liquefied asphalt. The resulting gelled asphalt cement is utilized in conventional processes for road paving, roofing, and specialty applications. The preferred organic acid component for the process is tall oil and the preferred alkali metal base is anhydrous sodium hydroxide.
A secondary feature of the asphalt compositions of the present invention is their ability to incorporate substantial amounts of crumb rubber from used automobile tires. A significant ecological problem is presented in the U.S. by the accumulation of used automobile tire carcasses which are very difficult to dispose of or to recycle into other uses. Various proposals have been made for incorporating crumb rubber from shredded used tires into asphalt paving compositions. However, the vulcanizing process used in manufacturing the tires, as well as the presence of various fillers, plasticizers, elastomers and other ingredients in the tires, make it very difficult to successfully incorporate crumb rubber from used tires into paving compositions. When blended into asphalt concrete compositions, the vulcanized rubber particles do not easily bond to the asphalt cement, and tend to separate from the composition. PCT International Publication WO93/17076 entitled "Asphalt Composition and Process for Obtaining Same," and the prior art patents and publications discussed therein, disclose a variety of prior art attempts to successfully incorporate ground rubber from automobile tires into asphalt paving or roofing compositions. Such efforts have not been commercially successful.